I believe the only people that got them were the groups who finished the Sin Dungeon. I think 4 or so groups finished this year, but I don't know if there were any given out at events in previous years.
As for a PC, it's whatever people value it. Its not the super desirable shadow color that everyone loves of the AoS robe, but when someone asked me to trade the Umbra robe for the AoS one, I said no. I feel like there are way more AoS shrouds than the Umbra, so I value Umbra more.
Sorry I can't give any numbers. No idea of even a ballpark figure.